Beyerite

Formula: CaBi2O2(CO3)2
Anhydrous carbonate
Specific gravity: 6.56
Hardness: 2 to 3
Streak: White
Colour: White to bright yellow, or greyish-green, grey; light yellow to colourless in transmitted light
Solubility: Readily soluble in acids with effervescence
Environments:

Pegmatites
Hydrothermal environments

Beyerite is a rare secondary mineral in hydrothermal mineral deposits and granite pegmatites, formed by alteration of bismuth-bearing sulfides and sulfosalts and associated with bismutite (common), bismutostibiconite, atelestite, preisingerite, pucherite, eulytine, namibite, clinobisvanite, bismutotantalite, bismuthinite and bismuth.

The type locality is Schneeberg, Erzgebirge, Saxony, Germany.

In three pegmatites in south-central Colorado, USA (Mica Lode and School Section deposits, Fremont county, and Meyers Ranch body, Park county), beyerite is inter-grown with bismutite. These minerals are supergene alterations of late, hydrothermal, metallic minerals, native bismuth, bismuthinite, and various bismuth-bearing sulfo-salts.